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Oklahoma’s four species of non-venomous watersnakes are often misidentified as the venomous northern cottonmouth. Avoid an unwanted snake encounters of watersnakes and northern cottonmouth by watching where you put your hands and feet. 

Oklahoma Watersnakes: The plain-bellied watersnake can be found statewide; the northern diamond-backed watersnake is found primarily in the body of the state; the common watersnake is found primarily in the eastern third of the state; and the broad-banded watersnake is restricted to the southeastern corner of Oklahoma. 

Watch Wild Double Take: Watersnakes and Northern Cottonmouth on YouTube.


Find tips for identifying Oklahoma’s look-alike species like waternakes and northern cottonmouth in our video series on YouTube.

Similarities: Oklahoma’s non-venomous watersnakes and the venomous northern cottonmouth are all large, heavy-bodied snakes. They are often found near permanent water sources where they typically eat fish and frogs. Though the snakes do have slightly different patterns, the watersnakes and the northern cottonmouth are largely dark in color. 

Differences: Watersnakes, in the genus Nerodia, are non-venomous. Like most other non-venomous snakes, they have rounded pupils. The northern diamond-backed watersnake has chain-like blotches and a yellow belly. The northern cottonmouth, however, is venomous, and has vertical pupils and a white line on the side of the mouth. Cottonmouths have heat-sensing pits and gets its name from its cottony white mouth. 

If you see a snake in your backyard, local park, or the larger Outdoor Oklahoma, consider sharing the sighting on the free nature platform iNaturalist. Adding a photo to your observation can allow others in the iNaturalist community to help confirm the identification. 

These Oklahoma look-alikes are included in the Wildlife Department’s “A Field Guide to Oklahoma’s Amphibians and Reptiles.” Tips for identification, a map of the Oklahoma range and information about the diet and preferred habitats are provided for 135 of the species that can be found in our state. The book’s spiral binding makes it easy to flip through and make comparisons of different species when identifying animals at home or in the field. Copies are available at